Exercise - Create models

• 2 minutes

By creating a model, you can define any essential fields and the behavior of your data. Let's add the necessary models for the dog_shelters application.

Create models

The first step in the process is to add the models. Django provides an empty file named models.py that you can use for your models.

1. Open the dog_shelters/models.py file in Visual Studio Code.

2. Add two Python classes to contain the models by entering the following code under the comment Create your models here:

   # Create your models here
   class Shelter(models.Model):
       name = models.CharField(max_length=200)
       location = models.CharField(max_length=200)
       def __str__(self):
           return self.name
   
   class Dog(models.Model):
       shelter = models.ForeignKey(Shelter, on_delete=models.PROTECT)
       name = models.CharField(max_length=200)
       description = models.TextField()
       intake_date = models.DateTimeField(auto_now_add=True)
       def __str__(self):
           return self.name
   

By adding these models, we now have a representation for shelters and dogs. Note the relationship between Dog and Shelter: a Shelter class can house many Dog values. Also note the auto_now_add value for intake_date. It automatically sets the field to the current date if a custom date isn't provided.

We're also using ForeignKey in the Dog class. This part tells Django there's a relationship between Dog and Shelter. By defining this relationship, we're telling Django that every dog is related to a single shelter.

Register the model

All applications must be registered with the project in Django. It might seem a little counterintuitive, but just because an application folder exists inside a project doesn't mean it automatically gets loaded. We need to register it by adding it to the INSTALLED_APPS list.

1. Find the configuration class name within the dog_shelters folder. To find this class name, go to the dog_shelters/apps.py file and check that the class name is DogSheltersConfig in the following code:

   class DogSheltersConfig(AppConfig):
       default_auto_field = 'django.db.models.BigAutoField'
       name = 'dog_shelters'
   

2. Open settings.py in project.

3. Add the full path to the class name under the comment #[TODO] - Add the app to the list of INSTALLED_APPS:

       #[TODO] - Add the app to the list of INSTALLED_APPS
       'dog_shelters.apps.DogSheltersConfig',
   

   The INSTALLED_APPS list now contains the following items:

   INSTALLED_APPS = [
       #[TODO] - Add the app to the list of INSTALLED_APPS
       'dog_shelters.apps.DogSheltersConfig',
       'django.contrib.admin',
       'django.contrib.auth',
       'django.contrib.contenttypes',
       'django.contrib.sessions',
       'django.contrib.messages',
       'django.contrib.staticfiles',
   ]
   

   Adding the line to the INSTALLED_APPS list tells Django that this app needs to be included when it runs the project.

Summary

You've now created two models for your Django application. Creating models is the foundation to all Django projects.